The objective of our investigation is to develop a theory of the mechanism of electroporation, by providing a quantitative description of key features of this dramatic phenomenon. Electroporation: is now believed to be a universal cell membrane phenomenon, involving both the lipid bilayer and membrane macromolecules, provides a general method for introducing molecules into cells, or releasing molecules from cells, with potentially major applications in science and technology, and yet is presently poorly understood. Our specific goals are: Extension of our first, successful theory of reversible electrical breakdown to one with more solid foundations, i.e. elimination of the approximate switch on criteria of pores. Development of a theory which describes quantitatively the transmembrane potential, U(t), during irreversible rupture, such that a unified theory of both REB and rupture is provided by one model. Extension of our first, successful theory of the reversible electrical breakdown of electroporation to include metastable pores associated with a pore-membrane macromolecule interaction. Development of a more complex theory which also predicts the amount of transmembrane transport of molecules. Keyword: Membranes biology, Biochemistry, Electrochemistry, Electric fields, Membrane channel proteins, Electrophoresis, Electroosmosis, Bioelectricity.